A Gram-stain-negative, non-spore-forming, aerobic, curved rod-shaped bacterium, designed strain R142T, was isolated from a coralline algae Tricleocarpa sp. in the Beibu Gulf, China. Optimal growth occurred with 0–0.5 % (w/v) NaCl, at 25 °C and at pH 8. Global alignment based on 16S rRNA gene sequences indicated that strain R142T shared 93.8 % similarity with its closest type strain, Pseudomaricurvus alkylphenolicus KU14GT. Phylogenetic analyses showed that strain R142T forms a distinct branch alongside Maricurvus nonylphenolicus KU41ET, Pseudoteredinibacter isoporae SW-11T, Pseudomaricurvus alkylphenolicus KU14GT, Pseudomaricurvus alcaniphilus MEBiC06469T and Aestuariicella hydrocarbonica SM-6T. The major polar lipids of strain R142T were phosphatidylethanolamine and phosphatidylglycerol. The primary cellular fatty acids were C16 : 0, C16 : 1ω7c, C18 : 1ω7c, C18 : 0 and C14 : 0. The genome DNA G+C ratio was 56.4 mol%. The only detected respiratory quinone was ubiquinone 8. The low 16S rRNA gene sequence similarity and differences in cellular fatty acids readily distinguished strain R142T from all validly published type strains. Strain R142T is therefore suggested to represent a novel species of a new genus, for which the name Exilibacterium tricleocarpae gen. nov., sp. nov. is proposed. The type strain of Exilibacterium tricleocarpae is R142T (=MCCC 1K03816T=KCTC 72138T).

A novel Gram-stain-negative, non-endospore-forming, motile, and aerobic bacterial strain, M105T, was isolated from coral Porites lutea, and was subjected to a polyphasic taxonomic study. Global alignment based on 16S rRNA gene sequences indicated that M105T shares the highest sequence identity of 94.5 % with Aliikangiella marina GYP-15T. The average nucleotide identity (ANI) and average amino acid identity (AAI) between M105T and A. marina GYP-15T was 69.8 and 71.6 %, respectively. On the basis of the results of phenotypic, chemotaxonomic, phylogenetic, phylogenomic, and comparative genomic analyses, it is concluded that M105T should represent a novel species in the genus Aliikangiella , for which the name Aliikangiella coralliicola sp. nov. is proposed. The type strain is M105T (=MCCC 1K03773T= KCTC 72442T). Furthermore, the family Kangiellaceae was classified into two families on the basis of phylogenetic, phylogenomic, polar lipid profile and motility variations. The novel family Pleioneaceae fam. nov. is proposed to accommodate the genera Aliikangiella and Pleionea .

A Gram-stain-negative, non-spore-forming, aerobic, motile, curved rod-shaped bacterium, designed strain R148T was isolated from a coralline algae Tricleocarpa sp. collected from Weizhou island, PR China. The optimal growth of R148T occurred at 25 °C, pH 8–9 in the presence of 0.5 % (w/v) NaCl on the basis of amended marine broth 2216. The genomic DNA G+C content was 59.5 mol%. The only detected respiratory quinone was Q-10. The major polar lipids were phosphatidylmethylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, and three unidentified ninhydrin-positive lipids. The major cellular fatty acids were C18 : 1ω7c, C16 : 1ω7c, C19 : 0cyclo 9, 10 DMA and C18 : 0. The results of 16S rRNA gene-based global alignment indicated that the closest neighbour of strain R148T was Pelagibius litoralis DSM 21314T (93.1 % similarity), the second is Limibacillus halophilus KCTC 42420T (92.2 %). The results of phylogenetic analysis indicated that R148T forms a distinct branch in the robust clade of R148T and P. litoralis DSM 21314T, while the taxonomic position of this clade in the family Rhodospirillaceae is ambiguous among phylogenetic approaches. The low 16S rRNA gene similarity and distinct polar lipid and cellular fatty acid profile could readily distinguish R148T from closely related type strains. So R148T is suggested to represent a novel species in a novel genus, for which the name Denitrobaculum tricleocarpae gen. nov., sp. nov. is proposed. The type strain is R148T (=MCCC 1K03781T=KCTC 72137T).

A novel Gram-stain-negative, non-endospore-forming, non-motile, aerobic bacterium (strain R33T) was isolated from coral Porites lutea and subjected to a polyphasic taxonomic study. The G+C content was 44.5 mol%. The only detected respiratory quinone was menaquinone 6 (MK-6). The major cellular fatty acids were iso-C15 : 0 and iso-C15 : 1 ω6c. The major polar lipids were phosphatidylethanolamine and two unidentified lipids. Global alignment based on 16S rRNA gene sequences indicated that strain R33T shares the highest sequence identity of 93.2 % with Muriicola marianensis A6B8T in the family Flavobacteriaceae . Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain R33T forms a distinct branch in a stable clade comprising strain R33T and members of the genera Muriicola , Robiginitalea , Eudoraea and Zeaxanthinibacter . The phylogenomic analysis also supported this 16S rRNA gene-based phylogenetic result. Comparative genomic analysis indicated that strain R33T is rich in AraC-type DNA-binding domain-containing protein-coding genes, which means the regulation of carbon utilization is very complex. Low 16S rRNA gene identity, different polar lipids and/or cellular fatty acid profiles could readily distinguish strain R33T from any validly published type strains. Therefore, strain R33T is suggested to represent a new species in a new genus, for which the name Poritiphilus flavus gen. nov., sp. nov. is proposed. The type strain is R33T (=MCCC 1K03853T=KCTC 72443T).